typedef struct {
RECT clip;
short ofs[2];
RECT tw;
u_short tpage;
u_char dtd;
u_char dfe;
u_char isbg;
u_char r0, g0, b0;
DR_ENV dr_env;
} DRAWENV;
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Members
| clip |
Drawing area.
clip specifies the rectangular area used for drawing. Drawing will not be performed outside the area specified by clip.
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| ofs |
Offset.
The values (ofs[0], ofs[1]) are used as offsets when calculating the address that is used for drawing in the frame buffer. The offsets are added to the values of all coordinates to determine the address used by drawing commands when drawing in the frame buffer. |
| tw |
Texture window.
tw specifies the rectangular area within the texture page that
is used repeatedly for applying textures.
|
| tpage |
Texture page initial value. |
| dtd |
Dither treatment flag
0: Dithering OFF.
1: Dithering ON.
|
| dfe |
Display area drawing flag
0: Drawing to the display area is disabled.
1: Drawing to the display area is enabled.
|
| isbg |
Clear drawing area flag
0: The drawing area is not cleared when the drawing environment is established.
1: The entire clipped area is painted with the brightness values (r0,g0,b0) when the drawing environment is established.
|
| r0, g0, b0 |
Background colour. Valid only when isbg = 1. |
| dr_env |
System reserved. |
Explanation
DRAWENV sets basic parameters related to drawing such as the drawing
offset and the drawing clip area.
Notes
Drawing can be performed in the region (0, 0)-(1023, 511) within the drawing space. Offsets and addresses to which the offset has been added are wrapped around at (-1024, -1024)-(1023, 1023). Values that can be specified for the texture window are limited to the combinations shown in the following table:
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tw.w
|
0(=256)
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16
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32
|
64
|
128
|
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tw.x
|
0
|
multiple of 16
|
multiple of 32
|
multiple of 64
|
multiple of 128
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tw.h
|
0(=256)
|
16
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32
|
64
|
128
|
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tw.y
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0
|
multiple of 16
|
multiple of 32
|
multiple of 64
|
multiple of 128
|
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